Aluminium hydroxide, Al(OH)3, is the most stable form of aluminium in normal conditions. It is found in nature as the mineral gibbsite (also known as hydrargillite).It can also be produced from bauxite ores by the Bayer Process. Closely related are aluminium oxide hydroxide, AlO(OH), and aluminium oxide, Al2O3, differing only by loss of water. These compounds together are the major components of the aluminium ore bauxite.In this process, bauxite ore is dissolved in sodium hydroxide at high temperatures to produce aluminium hydroxide and sodium aluminate. The aluminium hydroxide can easily be separated and purified. Gibbsite deposits are found as constituents of bauxite reserves, and the current largest bauxite producers are Australia, China, Brazil, India and Guinea.
Gibbsite has a typical metal hydroxide structure with hydrogen bonds. It is built up of double layers of hydroxyl groups with aluminum ions occupying two-thirds of the octahedral holes between the two layers.
Aluminum hydroxide is amphoteric. It dissolves in acid, forming Al(H2O)63+ or its hydrolysis products. It also dissolves in strong alkali, forming Al(OH)4–. Aluminum hydroxide is produced in the Bayer process as an intermediate in the production of aluminum metal.